In order to meet wireless data traffic demands, which have increased since the commercialization of a 4G communication system, efforts to develop an improved 5G communication system or a pre-5G communication system have been made. For this reason, the 5G communication system or the pre-5G communication system is called a beyond-4G-network communication system or a post-LTE system.
In order to achieve a high data transmission rate, implementation of the 5G communication system in an mmWave band (for example, a 60 GHz band) is being considered. In the 5G communication system, technologies such as beamforming, massive Multi-Input Multi-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, analog beam-forming, and large-scale antenna technologies are being discussed to mitigate propagation path loss in the mmWave band and increase propagation transmission distance.
Further, technologies such as an evolved small cell, an advanced small cell, a cloud Radio Access Network (cloud RAN), an ultra-dense network, Device-to-Device communication (D2D), a wireless backhaul, a moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation have been developed to improve the system network in the 5G communication system.
In addition, the 5G system has led to the development of Advanced Coding Modulation (ACM) schemes such as Hybrid FSK and QAM Modulation (FQAM) and Sliding Window Superposition Coding (SWSC), and advanced access technologies such as Filter Bank Multi Carrier (FBMC), Non-Orthogonal Multiple Access (NOMA), and Sparse Code Multiple Access (SCMA).
The communication standard of the mmWave band has considered only Single-Input Multiple-Output (SISO) transmission to date. However, when Multiple-Input Multiple-Output (MUMO) transmission is considered in the future, a propagation delay difference may occur between different types of beamforming signals, and accordingly, Inter-Symbol Interference (ISI) may occur between multiple antenna signals.
In general, a Cyclic Prefix (CP) interval should be sufficiently increased to solve the inter-symbol interference in an Orthogonal Frequency Division Multiplexing (OFDM) communication scheme. However, if the CP interval is increased, transmission power and transmission band efficiency may significantly decrease due to an increase in overhead. Conversely, when the OFDM symbol size is increased to reduce a CP ratio, it is difficult to estimate a phase error of an mmWave RF circuit and also to guarantee time coherence of channels within the symbol interval.